GPUVertBuf: GL Backend Isolation

Part of the Vulkan port T68990

This makes a few changes in how the data is being handled by the
backend to allow more flexibility in the future.

The overall code logic is left unchanged.

1 files changed, 57 insertions, 7 deletions

diff --git a/source/blender/gpu/intern/gpu_vertex_buffer_private.hh b/source/blender/gpu/intern/gpu_vertex_buffer_private.hh
index eb7e0bc8b9b..61af0a215a9 100644
--- a/source/blender/gpu/intern/gpu_vertex_buffer_private.hh
+++ b/source/blender/gpu/intern/gpu_vertex_buffer_private.hh
@@ -29,7 +29,8 @@
 
 namespace blender::gpu {
 
-struct VertBuf {
+class VertBuf {
+ public:
   static size_t memory_usage;
 
   GPUVertFormat format = {};
@@ -37,16 +38,65 @@ struct VertBuf {
   uint vertex_len = 0;
   /** Number of verts data. */
   uint vertex_alloc = 0;
-  /** 0 indicates not yet allocated. */
-  uint32_t vbo_id = 0;
-  /** Usage hint for GL optimisation. */
-  GPUUsageType usage = GPU_USAGE_STATIC;
   /** Status flag. */
   GPUVertBufStatus flag = GPU_VERTBUF_INVALID;
-  /** This counter will only avoid freeing the GPUVertBuf, not the data. */
-  char handle_refcount = 0;
   /** NULL indicates data in VRAM (unmapped) */
   uchar *data = NULL;
+
+ protected:
+  /** Usage hint for GL optimisation. */
+  GPUUsageType usage_ = GPU_USAGE_STATIC;
+
+ private:
+  /** This counter will only avoid freeing the GPUVertBuf, not the data. */
+  int handle_refcount_ = 1;
+
+ public:
+  VertBuf();
+  virtual ~VertBuf();
+
+  void init(const GPUVertFormat *format, GPUUsageType usage);
+  void clear(void);
+
+  /* Data manament */
+  void allocate(uint vert_len);
+  void resize(uint vert_len);
+  void upload(void);
+
+  VertBuf *duplicate(void);
+
+  /* Size of the data allocated. */
+  size_t size_alloc_get(void) const
+  {
+    BLI_assert(format.packed);
+    return vertex_alloc * format.stride;
+  }
+  /* Size of the data uploaded to the GPU. */
+  size_t size_used_get(void) const
+  {
+    BLI_assert(format.packed);
+    return vertex_len * format.stride;
+  }
+
+  void reference_add(void)
+  {
+    handle_refcount_++;
+  }
+  void reference_remove(void)
+  {
+    BLI_assert(handle_refcount_ > 0);
+    handle_refcount_--;
+    if (handle_refcount_ == 0) {
+      delete this;
+    }
+  }
+
+ protected:
+  virtual void acquire_data(void) = 0;
+  virtual void resize_data(void) = 0;
+  virtual void release_data(void) = 0;
+  virtual void upload_data(void) = 0;
+  virtual void duplicate_data(VertBuf *dst) = 0;
 };
 
 /* Syntacting suggar. */